Mesoscale Discussion 1649

Issued

Sep 16, 2017, 3:47 PM CDT (20:47 UTC)

Expired

Sep 16, 2017, 6:15 PM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Chance of a watch

40%

Counties Butler County, KS, Chase County, KS, Clay County, KS, Dickinson County, KS, Geary County, KS, Harvey County, KS, Jackson County, KS, Kingman County, KS, Lyon County, KS, Marion County, KS, McPherson County, KS, Morris County, KS, Pottawatomie County, KS, Reno County, KS, Riley County, KS, Saline County, KS, Sedgwick County, KS, Shawnee County, KS, Wabaunsee County, KS

The Wichita radar (KICT), 98 km from the middle of the area, began a volume at 20:47 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

711 
ACUS11 KWNS 162047
SWOMCD
SPC MCD 162047 
KSZ000-162315-

Mesoscale Discussion 1649
NWS Storm Prediction Center Norman OK
0347 PM CDT Sat Sep 16 2017

Areas affected...Portions of central and eastern KS

Concerning...Severe potential...Watch possible 

Valid 162047Z - 162315Z

Probability of Watch Issuance...40 percent

SUMMARY...A risk for severe thunderstorms may increase across parts
of central and eastern KS through the late afternoon hours and
continue into the evening. There is some possibility that Severe
Thunderstorm Watch issuance could become necessary during the next
few hours.

DISCUSSION...Visible satellite imagery indicates a shallow, dense,
swelling field of boundary-layer cumulus within the general apex
region of a pre-frontal thermal ridge permeating the western flank
of Gulf return moisture -- i.e. from Stafford and Rice Counties to
Ottawa County. The front enters northeast KS near Nemaha County and
extends southwestward, and mesoscale ascent is being bolstered near
a diffuse triple point in proximity to Comanche County. Deeper
convection may initiate from these zones of ascent in the 2130-2300Z
time frame -- initially being delayed by ample antecedent capping
associated within a moist-boundary-layer-overlying EML. Steep lapse
rates of 8.5-9 C/km in the mid levels, accompanying the EML, are
supporting 1500-2500 J/kg of MLCAPE in the warm/moist air mass. This
may yield a few robust updrafts, probably following the repeated
development and decay shallow convective plumes amidst only modest
frontal ascent.

A few sustained convective elements should be more likely by early
evening, with 25-30 kt of effective shear supporting small
forward-propagating clusters with isolated to widely scattered
severe wind/hail. This activity will spread eastward/northeastward,
reaching a corridor from Topeka and Lawrence toward Wichita by
evening. This activity will eventually ingest convectively processed
air from ongoing convection from the KC area to northeast OK. The
anticipated severe storm coverage is presently questionable with
stronger deep shear/ascent lagging behind the surface front, though
environmental and convective trends will be monitored for possible
Severe Thunderstorm Watch issuance.

..Cohen/Guyer.. 09/16/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...EAX...TOP...ICT...

LAT...LON   38219826 39149754 39579681 39789588 39399539 37639672
            37309790 37469838 38219826

Mesoscale Discussions in Kansas, 2017Every mesoscale discussion in 2017

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.